1. Field of the Invention
The present invention relates to the field of semiconductor processing; more specifically, it relates to an apparatus and method for aligning a solder bump mask to a substrate.
2. Background of the Invention
The formation of solder bumps or controlled collapse chip connection (C4) interconnects on semiconductor substrates requires assembly of an alignment fixture holding the substrate and a metal mask having holes through which the solder bump processes of sputter clean, pad limiting metallurgy evaporation and solder bump evaporation are performed. Prior to these process steps, the mask must be aligned to the substrate. Traditionally, alignment of mask to substrate has been done manually, however as solder bump sizes and spacing between solder bumps has decreased; manual alignment has been shown to be unable to provide the alignment accuracy needed.